I can only say that I usually turn off the mains power when the TV is not used.
When I turn it on (power + key pressure), there is some 50% than it shuts down automatically after some 1-2 minutes.
Second time it always turns on correctly.

For example, I've powered the TV on, I've pressed one key on the remote, I've pressed the "Home key" and I've chosen Net TV. Right after selecting one app, the TV was again off (red LED on).

I think that this is a #1 severity bug.

For Philips:
Is there a way to help you to get useful debug info from the jack on the rear or from a dump on the USB key..?

here you can get some info from another person passing the days finding and fixing bugs on firmware (not for consumer devices.. ).

When it happened (fw 14.97) I was using a new WD TV Live Streaming, connected to HDMI 3.
The TV turned off by itself just after mechanically turning on the TV, pressing the remote power button and waiting 1-2 minutes.

On HDMI 2 I have a HD Sat receiver (mechanically turned off when not used).
I never use the RF input and the internal DVB-T receiver.

Recently I have replaced the WiFi adapter with a better Cat 5E connection to a Netgear router. The problem did not disappear.

In the past (fw 14.93) I often saw the problem after mechanical turning the TV on, pushing the power key on the remote control and going to NetTV.

I've never seen a second "automatic" (automagic?) power-off event in a raw.

So, usually my TV does not stay in standby state for a long period waiting for being powered on.
May be there is a "grey" small time window between mechanical on and pressing the power button that may lead to the problem?

This time the source was the Satellite receiver. After seeing some dozens of seconds of sat video, the TV switched automatically to the off state (red LED on).
No problems after turning it on again (with remote power key).

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